clk: qcom: dispcc-sm8250: handle MMCX power domain

On SM8250 MMCX power domain is required to access MMDS_GDSC registers.
This power domain is expressed as mmcx-supply regulator property. Use
this regulator as MDSS_GDSC supply.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20201023131925.334864-6-dmitry.baryshkov@linaro.orgSigned-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/qcom/dispcc-sm8250.c

@@ -963,6 +963,7 @@ static struct gdsc mdss_gdsc = {
 	},
 	.pwrsts = PWRSTS_OFF_ON,
 	.flags = HW_CTRL,
+	.supply = "mmcx",
 };
 
 static struct clk_regmap *disp_cc_sm8250_clocks[] = {